How To Add Another Outlet For A Flat Panel Tv?

i am going to be mounting a flat panel tv to my wall. there is a power outlet at the bottom of the wall (which i can plug in cable box, dvd, etc.) but i want to add another outlet higher up on the wall behind the flatpanel tv. how do i go about taping off of the existing outlet? i am also going to add a bulk cable wall plate behind the tv and at the bottom of the wall (to run hdmi cables and stuff)